/Engine/Source/Editor/UMGEditor/Public/IHasDesignerExtensibility.h
Deprecated* AddDesignerExtension is deprecated, use the IDesignerExtensibilityFactory instead.
void AddDesignerExtension ( const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [FDesignerExtension](API\Editor\UMGEditor\FDesignerExtension) > & Extension )